The stability–instability paradox is an international relations theory regarding the effect of nuclear weapons and mutually assured destruction.
For instance, during the Cold War the United States and the Soviet Union never engaged each other in warfare, but fought proxy wars in Korea, Vietnam, Angola, the Middle East, Nicaragua and Afghanistan and spent substantial amounts of money and manpower on gaining relative influence over the third world.
[4] A study published in the Journal of Conflict Resolution in 2009 quantitatively evaluated the nuclear peace hypothesis, and found support for the existence of the stability–instability paradox.
The study determined that while nuclear weapons promote strategic stability, and prevent large scale wars, they simultaneously allow for more lower intensity conflicts.
With strategic interests forming the “red line” neither side would dare to cross, both sides are free to pursue sub-strategic political objectives through militarized conflict without the fear that the terms of such conflict will escalate beyond their control and jeopardize their strategic interests.